12.5 mm (1/2″) square drive. For screws with External TORX® profile. Socket bits made of CV steel. KnurledContents:1 socket bit ea. for screws with External TORX® profile in AF E 10, E 11, E 12, E 14, E 16, E 18, E 20, E 241 reducer, 12.5 mm (1/2″) to 10 mm (3/8″) external square